Filtration of solutions and the like



Patented June 28, 1927.

' UNITED STATES PATENT OFFICE."

JOSEPH BLUMENFELD, 01* LONDON, ENGLAND.

FILTRATION OF SOLUTIONS AND THE LIKE.

No Drawing. Application .flled July 28, 1924, Serial No. 728,785, and in Great Britain August 3, 1923.

This invention relates to thetreatment of solutions which may be termed unfiltrable with a view to rendering the separation therefrom-of suspended matter less difiicult -than heretofore.

The solutions obtained from the chemical attack upon minerals or products especially those containing metals of the fourth group such as titanium, zir-,

conium, thorium, tin, contain suspended matter which'cannot without. great difficulty be separated from the solution in the usual way as by filtering or decanting, and are those to which the invention relates.

The suspended matter referred to may comprise for example insoluble oxides such as SiO or any of the various metals originally present in the crude mineral, insoluble and unattached particles of the mineral in a finely divided state and other colloidal compounds introduced with the acid for example during the attack or resulting from the attack or other causes such as slight hydrolysis.

It. has previously been proposed to free a solution containing electro-positive colloids by coagulating therewith electro-negative colloidal sulphur and precipitating sulphur in the solution under oxidizing conditions. This has been efi'ected by the addition of 'sulphuretted hydrogen or. a sulphide in the presence of an oxidizing agent.

The present invention consists in treating solutions containing metallic elements of the fourth group, viz, titanium, zirconium, tin

or thorium for the rapid separation of suspendedinatter defined above therefrom by .the precipitation therein of colloidal metallic sulphides, under neutral or reducing conditions, whereby the impurities are precipitated together with the said metallic sulphides, and the solution so clarified. In the present invention the colloidal metallic sulphides are formed by double decomposition within the solution to beclarified, by the addition thereto of suitable substanceswhich react with one another under reducing conditions to produce the said sulphides, and heat may be applied when necessary. The colloidal metallic sulphide formed Within the solution carries an electric charge of op posite sign to the charge carried by the suspended matter which it is desired to remove Earample I.

Clarification of a solution of thorium. The said. solution may be that produced by the attack of hydrochloric acid on crude hydroxide of thorium, which solution has a density of 33 B6. and contains 150 grammes of ThO per litre. Clarification is effected by adding 3 5111. of a solution satu-' rated with copper sulphate to every litre of solution. The whole'is well mixed and iron sulphide is then added in a quantity sufficient to completely precipitate the copper in the form of a sulphide while the iron passes into solution to be subscqi icntly re-; moved with the iron originally present, in!

the solution.

The reactions taking place may be represented thus I The CuS formed as above carries an electric charge of opposite sign'to that carried by the impurities, and as a consequence mutual precipitation results. After a time, the resulting solution is filtered or allowed to stand and the clarified solution decanted from the mixed precipitate of copper sulphide and the impurities.

Ewampl'e H.

Clarification of a solution of titanium. The said solution may be that produced by the attack of sulphuric acid on ilmenite, which has a density of 50 B. and contains 200 grammes of TiO per litre. Heat is applied to the solution until a temperature of about 50 C. is reached when, for every litre of solution, 0.5 gramme of AS 0 previously dissolved in water is added. A

, "the solution to be clarified: an oxygen compou'ndof a metal Whose sulphide is insoluble prising adding to the solution compounds capable of forming by reaction Within said solution a, I colloidal metallic quantity of iron sulphide 'suflicient to com-' I pletely precipitate, the i I of'a sulphide is added; The reactions taking place may be represented thus I a Mutual precipitation occurs as in the pre- 'vious example.

the clarified solution decanted from the mixed precipitate of arsenic sulphide and the impurities.

, Having now describcdmy invention, what I'claim as new and. desire to secureby'Letters Patent is 2-- 1. A process for tions which result from chemical attack upon minerals or the like containing metallic ele- I said process comments ofthe fourth group,

to be clar fied sulphide having an electric charge of 0pposite'sign to that of said 2. A process for the clarification of by I theremoval otlsuspended matter trom'solu- 'tions which result from chemical attackupon minerals or the like coi'it'ainingtin, titanium,

thorium'or zirconium, comprising adding to in said solution, and a metallic sulphur compound capable of: liberating H S Within the solution to precipitate therein the said insoluble sulphide.

3.' A process as claimed in claim 1, comarsenic in the form After precipitation, the "solution is'filteredor allowed'to stand and prising I v the clarification ofby' the removal of suspended matter from solu suspended matter.

prising heating I the solution to be treated, and adding thereto 'l'netallic compounds ca-v pable of formin therein by double decom- I I position a colloidalmetallic sulphide, allow- 7 ing the resulting solution to stand and there. after decanting or filtering it.

4. 'A. process as claimed in claim 2, comprising heating the solution to be treated and adding thereto metallic compounds capable offorming therein aninsoluble colloidal I metallic sulphide, allowing the resulting solution' to stand and thereafter decanting or filtering it. V

5. A process adding to the solution to be treated a metallic 7 S111 hate and iron sulphide; the latter in quantity capable of completely convcrtingby double decomposition the said prising adding to ing said solutions to an equivalent quantity of iron sulphide,

tion.

minerals and products as contain 'm'etals'of theffourth group and other elements or compounds of which enter and exist in such solutions in a finely divided or colloidal state, characterized by being'substantially tree from'suspended or, colloidal matter.

In testimony whereof I have signed my name to this specification.

J. BLUMENFELD.

as claimed inclaimfi, com

Solutions obtainued by direotchemical attack upon such I I and thereafterseparating the resultingsolu- '5 tion and precipitate by filtration or decanta' 

